Various circuit testers have been developed for testing the correctness of the wiring of three-wire ground type electrical household outlets or receptacles. A number of these devices comprise three lamps connected between the prongs of a three-prong standard plug and disposed within a suitable housing. When such a circuit tester is plugged into the outlet being tested the combinations of energized lamps indicate whether or not the wiring of the outlet is correct.
However, modular wiring systems have been created that would provide the ability to test wiring before conventional wall receptacles have been installed. Providing a mechanism to test these modular wiring systems would allow for problems to be caught earlier on in the installation process and would require less disassembly, since the conventional receptacle or wall switch would not yet be installed. Furthermore, providing a device that is capable of testing both conventional receptacles and modular wiring systems in a single device would eliminate the need to carry multiple testers. Finally, conventional testers with add-on features to test additional components typically include circuitry that interconnects all of the testing components. This leads to situations where, when one portion of the tester is being used, the other portions must be covered, retracted or switched to a non-enabled state to prevent a shock hazard. Providing an electrical testing device with electrically separate testing systems eliminates the potential for shock hazard, and provides the ability to test multiple types of devices simultaneously.